A medical apparatus such as endoscope, which is not disposable, is directly contacted with patients and therefore needs a safer sterilization for use in subsequent examinations and the like. However, especially in small scale hospitals, a single apparatus is often repeatedly used in a short period of time. Under these circumstances, a composition which have action of killing wide variety of microorganisms and ability of sterilizing a medical apparatuses in a short period of time is desired as a composition for sterilization of a medical apparatus. Further, from a viewpoint of safety, an amount of chemical compounds in the composition is required to be as small as possible.
As a composition for cleaning and sterilizing a medical apparatus such as endoscope, a composition containing an aldehyde such as glutaraldehyde as an active ingredient is conventionally known as a commercial product. However, glutaraldehyde is recently reported to have a weak sterilizing effect to spores and may be a cause of allergies.
A composition for sterilization is also known which contains a peracetic acid as an active ingredient. However, because peracetic acid has irritating smell derived from a peracid as well as strong smell of acetic acid, a practical use of a peracetic acid as a disinfectant will be a burden on an operator, and further an equipment such as ventilation is essential. An aliphatic peroxycarboxylic acid such as peroxypropionic acid is reported to have effective sterilizing action (J. Hyg. Epid. Microbiol. Immun., 9, pp. 220-226 (1965)). However, the aliphatic peroxycarboxylic acids as mentioned above also have a problem of unpleasant smell. The unpleasant smell of the aliphatic peroxycarboxylic acid will be weaker as where the number of carbon atoms increases. When the acid is liner, those having 11 or more carbon atoms have almost no smell. However, they have another problem of insolubility in water and cannot be used for preparation of an aqueous composition which is suitable for sterilization of a medical apparatus.
As a means for solving the problem of the unpleasant smell of the aliphatic peroxycarboxylic acid, use of a peroxycarboxylic acid which is a divalent carboxylic acid is disclosed in Japanese Patent Unexamined Publication (Kokai) No. (Hei) 8-67667. However, a result of an experiment by the inventors of the present invention reveals that an antibacterial effect of the peroxycarboxylic acid is weaker than that of peracetic acid. Japanese Patent Unexamined Publication (Kohyo) No. (Hei) 10-501805 discloses that a peroxycarboxylic acid having an ester group has almost the same degree of antibacterial effect as that of peracetic acid. However, the acid has a problem that, when a peroxycarboxylic acid is synthesized, the ester moiety is susceptible to hydrolysis because a strong acid such as sulfuric acid is used as a reaction catalyst in an aqueous solution.
Peroxymethoxyacetic acid, which is disclosed in J. Molecular Catalysis B: Enzymatic, 19-20, pp. 499-505 (2002), is reported to have weaker antibacterial effect than that of peracetic acid. Nippon Kagaku Zassi (Journal of chemistry in Japan) 87, pp. 476-505, (1966) reports that for a peroxycarboxylic acid such as peroxy chloroacetic acid, substitution with an electron withdrawing group at 2-position will deteriorates stability of the acid. Therefore, peroxymethoxyacetic acid, which is substituted with electron withdrawing methoxy group at 2-position, is expected to have less stability than peracetic acid. As described above, the attempts for reducing the unpleasant smell of peracetic acid have not successfully become practical applications from viewpoints of poor antibacterial effect and lack of formulation suitability.
From an aspect of compounds, an aliphatic peroxycarboxylic acid which has an alkoxy group at 3-position has not been reported so far, and its sterilization activity is not known. Japanese Patent Unexamined Publication (Kohyo) No. 2000-505136 discloses peroxycarboxylic acids represented by the formula Y—Ra—COOOH (wherein Y represents HO(CH2CH2O)n (wherein n represents an integer of 1 to 40, Ra represents a C1-C30 alkylene group). However, Y is limited to an ethylene oxide group in the acid, and the publication only discloses compounds wherein Y is hydroxyalkyloxy group. Further, the publication does not disclose data relating to sterilization effects of the acids. The aforementioned J. Molecular Catalysis B: Enzymatic, 19-20, pp. 499-505 (2002) discloses peroxymethoxyacetic acid, however, it fails to disclose an aliphatic peroxycarboxylic acid having an alkoxy group at 3-position.